added a comment clarifying the indirection

wjakob · wjakob · commit 411fd55cb86c · 2022-11-25T16:01:20.000+01:00
diff --git a/Lib/typing.py b/Lib/typing.py
@@ -352,6 +352,11 @@ def _tp_cache(func=None, /, *, typed=False):
     original function for non-hashable arguments.
     """
     def decorator(func):
+        # The callback 'inner' references the newly created lru_cache
+        # indirectly by performing a lookup in the global '_caches' dictionary.
+        # This breaks a reference that can be problematic when combined with
+        # C API extensions that leak references to types. See GH-98253.
+
         cache = functools.lru_cache(typed=typed)(func)
         _caches[func] = cache
         _cleanups.append(cache.cache_clear)
